Vehicles of the type known as "articulated vehicles" or "articulated frame structures" currently enjoy wide-spread acceptance by the construction industry. Typically such vehicles are made in two sections, a front or forward unit and a rear or back unit. These two sections are joined by an articulated joint. Typical examples are described in U.S. Pat. No. 3,038,619; 3,912,300 and 4,154,456.
Articulated vehicles employing an articulated joint which accommodates relative pivotal movement between the two sections of the vehicle both with respect to a vertical axis and with respect to a horizontal axis have heretofore been highly complicated in design and therefore expensive to manufacture. Very often, complicated bearing structures were used which required frequent maintenance and which were subject to wear or breakage. Space was restricted and surrounding equipment could not interfere with the operation of the joint.
Specifically, the pivotal axis of the joint is relatively inaccessible and not readily visible. The joint is therefore frequently ignored from the standpoint of maintenance. This is even true though the joint is subject to substantial wear due to dirt and other contaminants entering therein.
Furthermore, since most of the control functions are of necessity located on the frame section with the material handling unit thereon, provision must be made for interconnecting these controls with the power plant. The power plant is usually located in the rear section to counterbalance the material handling unit. Power transfer is normally accomplished through hydraulic plumbing and electrical wiring. With a center articulated joint, it often becomes difficult to find adequate space for passing these connections between the two frame sections.
One highly successful and typical articulated vehicle of the type just described is described in U.S. Pat. No. 4,154,456 by Jensen et al. and assigned to the assignee of the present invention. One of the sections has an elongated guide channel that extends generally transversely of the longitudinal axis thereof with a support member movable along the guide channel. A first universal joint connection is provided between the support member and the other frame section while a second universal connection is provided directly between the two frame sections at a location spaced from the guide channel. Thus, the second universal connection not only provides a connection between the two frame sections that will accommodate pivotal movement about the vertical axis, but also defines a general, horizontal longitudinal pivot axis between the two frame sections.
More specifically, a channel member cooperates with the guide channel to maintain a U-shaped support member on the guide channel and also to define extreme limits of movement of the support member along the guide channel. Spacers are positioned between the guide channel and the channel member at opposite ends with bolts used to interconnect the two channels. The spacers not only maintain the predetermined clearance between the two channels, but also define extreme limits of movement along the guide channel. Wear plates are secured to opposite surfaces of the base portion of the U-shaped support bracket. These wear plates are ideally kept in continuous engagement with the adjacent surfaces of the two channels.